The present disclosure relates to systems, compositions, and methods for treating subterranean formations.
The unwanted production of water, including brine, from hydrocarbon-producing wells constitutes a considerable technical problem and expense in oilfield operations. When a subterranean formation contains water in significant amounts (e.g., aquifers) and/or where water is injected into the formation in order to improve the hydrocarbon recovery, the higher mobility of the water often allows it to flow to the well bore by way of natural and manmade fractures and high permeability streaks. If the ratio of recovered water to recovered hydrocarbons becomes sufficiently large, the cost of separating the water from the hydrocarbons and disposing of it can become a barrier to continued production. This can lead to abandonment of a well penetrating a subterranean formation, even when significant amounts of hydrocarbons remain therein.
In order to reduce the undesired production of water from hydrocarbon-producing subterranean formations, aqueous-soluble polymer systems containing crosslinking agents have been used in the art to enter water-containing zones of the formation and block the flow of water therefrom. Selective placement of these crosslinked polymers in a subterranean formation and stability therein represent significant technical challenges that have somewhat limited their use. A more recent strategy to reduce water production from a subterranean formation has been to use agents known as relative permeability modifiers (RPMs). Such RPMs are capable of significantly reducing the flow of water within a subterranean formation while having a minimal effect on the flow of hydrocarbons. The use of RPMs does not generally necessitate the use of zonal isolation techniques that are often employed with crosslinked polymers.
While RPMs can overcome the necessity for selective placement in a subterranean formation, it may still prove advantageous to place RPMs in a desired zone of a subterranean formation in order to more efficiently focus their effects therein. For example, typical uses of RPMs involve injecting a fluid carrying the RPM into the matrix of the rock formation. However, certain regions of a formation often contain one or more fractures or voids, which may be naturally-occurring and/or may be created or enhanced in the course of one or more subterranean operations (e.g., fracturing, acidizing, drilling, etc.). In such regions, there may be insufficient rock matrix into which to place the RPM, and thus those regions may remain susceptible to unwanted production of water despite having been exposed to an RPM.
While embodiments of this disclosure have been depicted, such embodiments do not imply a limitation on the disclosure, and no such limitation should be inferred. The subject matter disclosed is capable of considerable modification, alteration, and equivalents in form and function, as will occur to those skilled in the pertinent art and having the benefit of this disclosure. The depicted and described embodiments of this disclosure are examples only, and not exhaustive of the scope of the disclosure.